1. Field of the Invention
This invention relates generally to apparatus for reproducing color video signals recorded, for example, on a magnetic tape, and more particularly is directed to an improved signal processing circuit for a color video signal reproducing apparatus.
2. Description of the Prior Art
It is known that, in recording a color video signal, the luminance component of the video signal is frequency-modulated to occupy a higher frequency band and the chrominance component has its carrier frequency-converted to occupy a lower frequency band below that of the frequency-modulated luminance component, whereupon the modulated luminance component and the converted chrominance component are combined to form a composite signal which is recorded on a magnetic tape. During reproducing, after the reproduced composite signal has been separated into the frequency-modulated luminance component and the frequency-converted chrominance component, on the basis of the frequency bands thereof, the luminance component is demodulated and the chrominance component is reconverted to the original or standard frequency band, and then both components are recombined to obtain the original color video signal. Such a magnetic recording and/or reproducing apparatus is usually provided with an automatic frequency control (AFC) circuit and an automatic phase control (APC) circuit for cancelling or correcting any time-based error included in the chrominance component of the reproduced composite signal. In the usual AFC circuit, horizontal synchronizing signals separated from the luminance component of the reproduced color video signal are compared with a suitably divided output of a voltage controlled variable frequency oscillator (VCO) to provide a control voltage by which the output frequency of the VCO is regulated, and the output of the VCO is employed as a frequency-reconverting signal by which the frequency-converted chrominance component of the reproduced color video signal has its carrier restored to a standard frequency, as in a frequency-converter.
Further, conventional color video signal recording and/or reproducing apparatus is usually provided with a dropout compensating circuit in its reproduced signal processing circuit. Such a drop-out compensating circuit is responsive to a drop-out in the luminance component of the reproduced color video signal for inserting in such luminance component, in the interval of the detected drop-out, an earlier occurring portion of the luminance component.
However, if the reproduced signal processing circuit or system of a color video signal recording and/or reproducing apparatus is provided with both a drop-out compensating circuit and an AFC circuit, as aforesaid, the horizontal synchronizing signals separated from a portion of the luminance component which has been compensated for drop-out, that is, in which an earlier occurring portion of the luminance component has been inserted, may not accurately correspond to the time-based error of the reproduced video signal and, accordingly, will disturb the operation of the AFV circuit so that a color image or picture formed on a color picture tube in response to the processed color video signals will be deteriorated.